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Atmospheric Crude Tower with Aspen HYSYS® V8.0 1. Lesson Objectives
Assign petroleum pe troleum assay assay to stream
Configure column col umn pre-heater
Configure crude tower
2. Prerequisites
Aspen HYSYS V 8.0
Introduction to distill ation
3. Background Oil refi re fineries neries take crude oil and separate it into more usef ul/valuable ul/valuable products such such as naphtha, diesel, kerosene, kerosene , and gas gas oil. An atmospheric distillation column column is one of the many unit operations that can can be found fou nd in an oil refine re finery. ry. Crude oil is fed into the atmospheric distillation disti llation column and several fractions are are produced which are then fe d to other process units such as hydrotreaters, hydrocrackers, hydrocrackers, reformers, and vacuum distill disti llation ation columns. In this lesson we will be focusin focusi ng solely on the atmosphe ric crude unit. The examples example s presented are are solely intended to illustrat ill ustrate e specific concepts and principles. They may may not reflect refle ct an industrial application application or real si tuation.
4. Problem Statement and Aspen HYSYS Solution Problem Statement In this thi s simulation we wi sh to simulate an atmospheric atmospheric crude fractionator. fractionator. 100,0 100,000 00 barrel/day of A rabian Light Light crude is fed to a f urnace that that will wi ll vaporize a portion of the crude. crude. This crude crude stream is then the n fed to an atmospheric crude column. column. The column will op erate with three coupled side strippers and and three pump around around circuits.
Aspen HYSYS Solution 4.01.
Create Create a new simulation in Aspen HYSYS V8.0. V8.0.
4.02.
Create a component list. li st. In the Component List f List f older, select Add. Add. Add Water, Water, Methane, Methane, Ethane, Ethane , Propane, Propane, i-Butane, i-Butane, and n-Butane to n-Butane to the component component list.
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4.03.
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Select option to Add hypotheticals to the component list. In the Component List – 1 form, change the Select option Hypothetical. Hypothetical. Enter an Initial Boiling Point of Point of 30°C, 30°C, a Final Boiling Boili ng Point of 900°C, 900°C, and an Interval of 10°C. 10°C. Click Generate Gene rate Hypos Hypos to to generate a hypothetical group.
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4.04.
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After generating the hypothetical group, click Add All to add all generated hypotheticals to the component list.
4.05.
Define property package. In the Fluid Packages folder select Add. Select Peng-Robinson as the property package.
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4.06.
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We wil l now characterize our crude oil. Go to the Petroleum Assays folder. Click Add. Enter Arabian Light for Name, select Specified for Assay Source, and select Basis-1 for Fluid Package.
4.07.
In the Arabian Light form, select Import From. A window will appear, select Assay Library.
4.08.
The Assay Library window will appear. Since we wish to model the Arabian Light crude, we will select Middle East for Region Name, and Saudi Arabia for Country Name. We can then select Arabian Light and click Import Selected Assay.
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4.09.
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After a few moments the disti llation cut data for the Arabian Light crude will populate the Assay Property form.
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4.10.
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Go to the Light Ends form to enter data for the light components to be included in the crude. Enter the following Volume % for each component. Check the box for Input and enter a Total Percentage of 1.4. This means that the specifi ed light ends will comprise 1.4 percent of the total crude.
4.11.
Move back to the Assay Property form and click Calculate Assay. After a few moments the status bar should turn green and say OK. You can go to the Results tab to vi ew a true boiling point (TBP) curve, composition data, and bulk properties of the crude, among other results.
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4.12.
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We are now ready to move to the si mulation environment to begin creating our flowsheet. Click the Simulation button in the bottom left of the screen.
4.13.
In the Home ribbon, change the units to Field units.
4.14.
Add a material stream to the flowsheet. This will be our crude feed which will be heated by a furnace and then fed to the distil lation column.
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4.15.
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Double click the material stream and rename it Raw Crude. Enter a Temperature of 77°F, a Pressure of 58.02 psia (4 bar), and a Std Ideal Liq Vol Flow of 100,000 barrels/day.
4.16.
We must now attach the petroleum assay to this stream. Go to the Petroleum Assay form and select Petroleum Assay From Library. Next, select Arabian Light. You wil l notice that the stream compositions will populate and the stream will solve.
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4.17.
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If you go to the Composition form you will see that the composition f or all hypothetical components and li ght ends are complete.
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4.18.
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We will now add a Heater block to the flowsheet. This will serve to pre-heat the crude stream and prepare it to enter the distil lation column.
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4.19.
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Double click the heater block ( E-100). Select Raw Crude as the Inlet stream, create an Outlet stream called ColumnFeed, and create an Energy stream called Q-Heat.
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4.20.
In the Parameters form, enter a Delta P of 7.252 psi (0.5 bar).
4.21.
In the Worksheet tab enter an outlet Temperature of 626°F. The heater should solve.
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4.22.
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Before adding the column to the flowsheet, we must first defi ne the steam and energy streams that will be used by the column. Add 3 Material Streams to the flowsheet. Name them Main Steam, Diesel Steam, and AGO Steam.
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4.23.
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Double click on each steam stream and enter the following information. Enter a Mole Fraction of 1 for Water for each stream as well. Stream Name Main Steam Ago Steam Diesel Steam
4.24.
Vapor Fraction 1 1 1
Pressure (psia) 145 145 145
Mass Flow (lb/hr) 6614 2205 2205
Add an Energy stream called Q-Trim. This stream does not require any specifications; it will be calculated by the column.
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4.25.
Add a Blank Column Sub-Flowsheet from the Model Palette.
4.26.
A window will appear, select Read an Existing Column Templ ate.
4.27.
Select template 3sscrude.col and click Open.
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4.28.
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The column property window will appear. On the Design | Connections form, you can vi ew all the internal streams withi n the column sub-flowsheet. The first thing we must do is connect the Internal and External Streams as shown below. Also enter a top stage pressure of 14.5 psia and a bottom pressure of 20.31 psia.
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4.29.
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We must now modify the stage locations for the side strippers and pump arounds. Go to the Side Ops tab. In the Side Strippers form select the following Liq Draw and Vap Return Stages.
4.30.
In the Pump Arounds form select the following Draw and Return Stages.
4.31.
We must now define the column operating specifications. Go to the Specs form under the Design tab. You will notice that in order to run this column you must define 13 specifications. The table below summarizes the design specifications chosen for this column. Specification Reflux Ratio Condenser Temp Kerosene D86 95% Temperature Diesel D86 95% Temperature AGO TBP 95% Temperature Pump Around 1 Return Temp Pump Around 2 Return Temp Pump Around 3 Return Temp Vapour Flow off condenser Kerosene SS Duty Pump Around 1 Draw Rate Pump Around 2 Draw Rate Pump Around 3 Draw Rate
4.32.
Spec Value 1 110°F 520°F 665°F 885°F 175°F 310°F 450°F 0 kgmole/h 3.966 MMBtu/hr 15,100 barrel/day 15,100 barrel/day 15,100 barrel/day
In the Specs form it may be easiest to initially delete all of the default specifications for the column.
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4.33.
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Click Add to add each desi gn specification one by one. The following pages will include a screenshot of each individual specification window. Reflux Ratio
Condenser Temperature
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Kerosene D86 95% Temperature
The D86 95% stream property is found under the Petroleum branch after clicking Select Property.
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AGO TBP 95% Temperature
The TBP 95% stream property is found under the Petroleum branch after clicking Select Property.
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Pump Around 2 Return Temperature
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Vapour Flow off condenser
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Pump Around 1 Draw Rate
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Pump Around 3 Draw Rate
4.34.
Once all 13 specifications are entered you should notice that the Degrees of Freedom is now 0. This means that the column is ready to begin calculations.
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4.35.
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Before we run the column, we wi ll enter top and bottom stage temperature estimates to help the column to converge. Go to the Profiles form under the Parameters tab. Enter a Condenser temperature of 110°F and a Stage 29 temperature of 630°F. The bottom stage temperature estimate was chosen because we know the column fee d stream is being fed into stage 29, therefore the stage 29 temperature should be around the same temperature.
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4.36.
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Click the Run button and the column will be gin calculations. After a few moments the column should converge.
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4.37.
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Check results. Go to the Summary form under the Performance tab. Here you can view the flowrates and compositions for each product stream. Note that Arabian Light is a l ight crude, therefore there is a large flowrate for the light products in the naptha stream, and lower flowrates for kerosene, diesel, and gas oil.
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5. Conclusions In this lesson we learned how to model a petroleum assay and assign a stream to an assay. We also learned how to insert and configure an atmospheric crude tower to produce petroleum products. A light crude, such as Arabian Light, will produce a high quantity of li ght products such as gasoline and naptha, while a heavie r crude will produce a higher quantity of heavier products such as kerosene, diesel, and fuel oil.
6. Copyright Copyright © 2012 by Aspe n Technology, Inc. (“AspenTech”). All rights reserved. This work may not be reproduced or distributed in any form or by any means without the prior written consent of AspenTech. ASPENTECH MAKES NO WARRANTY OR REPRESENTATION, EITHER EXPRESSED OR IMPLIED, WITH RESPECT TO THIS WORK and assumes no liabi lity for any errors or omissions. In no event will AspenTech be liable to you for damages, including any loss of profits, l ost savings, or other incidental or consequential damages arising out of the use of the information contained in, or the digital fi les supplied with or for use with, this work. This work and its contents are provided for educational purposes only.
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